/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.obfuscate;

import proguard.classfile.*;
import proguard.classfile.util.*;
import proguard.classfile.visitor.MemberVisitor;

import java.util.*;

/**
 * This MemberVisitor obfuscates all class members that it visits. It uses names from the given name factory. At the
 * same time, it avoids names from the given descriptor map.
 * <p>
 * The class members must have been linked before applying this visitor.
 *
 * @see MethodLinker
 *
 * @author Eric Lafortune
 */
public class MemberObfuscator extends SimplifiedVisitor implements MemberVisitor {
    private final boolean allowAggressiveOverloading;
    private final NameFactory nameFactory;
    private final Map descriptorMap;

    /**
     * Creates a new MemberObfuscator.
     * 
     * @param allowAggressiveOverloading a flag that specifies whether class members can be overloaded aggressively.
     * @param nameFactory the factory that can produce obfuscated member names.
     * @param descriptorMap the map of descriptors to [new name - old name] maps.
     */
    public MemberObfuscator(boolean allowAggressiveOverloading, NameFactory nameFactory, Map descriptorMap) {
        this.allowAggressiveOverloading = allowAggressiveOverloading;
        this.nameFactory = nameFactory;
        this.descriptorMap = descriptorMap;
    }

    // Implementations for MemberVisitor.

    public void visitAnyMember(Clazz clazz, Member member) {
        // Special cases: <clinit> and <init> are always kept unchanged.
        // We can ignore them here.
        String name = member.getName(clazz);
        if (ClassUtil.isInitializer(name)) {
            return;
        }

        // Get the member's descriptor.
        String descriptor = member.getDescriptor(clazz);

        // Check whether we're allowed to overload aggressively.
        if (!allowAggressiveOverloading) {
            // Trim the return argument from the descriptor if not.
            // Works for fields and methods alike.
            descriptor = descriptor.substring(0, descriptor.indexOf(')') + 1);
        }

        // Get the name map, creating a new one if necessary.
        Map nameMap = retrieveNameMap(descriptorMap, descriptor);

        // Get the member's new name.
        String newName = newMemberName(member);

        // Assign a new one, if necessary.
        if (newName == null) {
            // Find an acceptable new name.
            nameFactory.reset();

            do {
                newName = nameFactory.nextName();
            } while (nameMap.containsKey(newName));

            // Remember not to use the new name again in this name space.
            nameMap.put(newName, name);

            // Assign the new name.
            setNewMemberName(member, newName);
        }
    }

    // Small utility methods.

    /**
     * Gets the name map, based on the given map and a given descriptor. A new empty map is created if necessary.
     * 
     * @param descriptorMap the map of descriptors to [new name - old name] maps.
     * @param descriptor the class member descriptor.
     * @return the corresponding name map.
     */
    static Map retrieveNameMap(Map descriptorMap, String descriptor) {
        // See if we can find the nested map with this descriptor key.
        Map nameMap = (Map)descriptorMap.get(descriptor);

        // Create a new one if not.
        if (nameMap == null) {
            nameMap = new HashMap();
            descriptorMap.put(descriptor, nameMap);
        }

        return nameMap;
    }

    /**
     * Assigns a fixed new name to the given class member.
     * 
     * @param member the class member.
     * @param name the new name.
     */
    static void setFixedNewMemberName(Member member, String name) {
        VisitorAccepter lastVisitorAccepter = MethodLinker.lastVisitorAccepter(member);

        if (!(lastVisitorAccepter instanceof LibraryMember) && !(lastVisitorAccepter instanceof MyFixedName)) {
            lastVisitorAccepter.setVisitorInfo(new MyFixedName(name));
        } else {
            lastVisitorAccepter.setVisitorInfo(name);
        }
    }

    /**
     * Assigns a new name to the given class member.
     * 
     * @param member the class member.
     * @param name the new name.
     */
    static void setNewMemberName(Member member, String name) {
        MethodLinker.lastVisitorAccepter(member).setVisitorInfo(name);
    }

    /**
     * Returns whether the new name of the given class member is fixed.
     * 
     * @param member the class member.
     * @return whether its new name is fixed.
     */
    static boolean hasFixedNewMemberName(Member member) {
        VisitorAccepter lastVisitorAccepter = MethodLinker.lastVisitorAccepter(member);

        return lastVisitorAccepter instanceof LibraryMember || lastVisitorAccepter instanceof MyFixedName;
    }

    /**
     * Retrieves the new name of the given class member.
     * 
     * @param member the class member.
     * @return the class member's new name, or <code>null</code> if it doesn't have one yet.
     */
    static String newMemberName(Member member) {
        return (String)MethodLinker.lastVisitorAccepter(member).getVisitorInfo();
    }

    /**
     * This VisitorAccepter can be used to wrap a name string, to indicate that the name is fixed.
     */
    private static class MyFixedName implements VisitorAccepter {
        private String newName;

        public MyFixedName(String newName) {
            this.newName = newName;
        }

        // Implementations for VisitorAccepter.

        public Object getVisitorInfo() {
            return newName;
        }

        public void setVisitorInfo(Object visitorInfo) {
            newName = (String)visitorInfo;
        }
    }
}
